function MediumEditor(elements, options) {
    'use strict';
    return this.init(elements, options);
}

if (typeof module === 'object') {
    module.exports = MediumEditor;
}

(function (window, document) {
    'use strict';

    function extend(b, a) {
        var prop;
        if (b === undefined) {
            return a;
        }
        for (prop in a) {
            if (a.hasOwnProperty(prop) && b.hasOwnProperty(prop) === false) {
                b[prop] = a[prop];
            }
        }
        return b;
    }

    // http://stackoverflow.com/questions/5605401/insert-link-in-contenteditable-element
    // by Tim Down
    function saveSelection() {
        var i,
            len,
            ranges,
            sel = window.getSelection();
        if (sel.getRangeAt && sel.rangeCount) {
            ranges = [];
            for (i = 0, len = sel.rangeCount; i < len; i += 1) {
                ranges.push(sel.getRangeAt(i));
            }
            return ranges;
        }
        return null;
    }

    function restoreSelection(savedSel) {
        var i,
            len,
            sel = window.getSelection();
        if (savedSel) {
            sel.removeAllRanges();
            for (i = 0, len = savedSel.length; i < len; i += 1) {
                sel.addRange(savedSel[i]);
            }
        }
    }

    // http://stackoverflow.com/questions/1197401/how-can-i-get-the-element-the-caret-is-in-with-javascript-when-using-contentedi
    // by You
    function getSelectionStart() {
        var node = document.getSelection().anchorNode,
            startNode = (node && node.nodeType === 3 ? node.parentNode : node);
        return startNode;
    }

    // http://stackoverflow.com/questions/4176923/html-of-selected-text
    // by Tim Down
    function getSelectionHtml() {
        var i,
            html = '',
            sel,
            len,
            container;
        if (window.getSelection !== undefined) {
            sel = window.getSelection();
            if (sel.rangeCount) {
                container = document.createElement('div');
                for (i = 0, len = sel.rangeCount; i < len; i += 1) {
                    container.appendChild(sel.getRangeAt(i).cloneContents());
                }
                html = container.innerHTML;
            }
        } else if (document.selection !== undefined) {
            if (document.selection.type === 'Text') {
                html = document.selection.createRange().htmlText;
            }
        }
        return html;
    }

    // https://github.com/jashkenas/underscore
    function isElement(obj) {
        return !!(obj && obj.nodeType === 1);
    }

    MediumEditor.prototype = {
        defaults: {
            allowMultiParagraphSelection: true,
            anchorInputPlaceholder: 'Paste or type a link',
            anchorPreviewHideDelay: 500,
            buttons: ['bold', 'italic', 'underline', 'anchor', 'header1', 'header2', 'quote'],
            buttonLabels: false,
            checkLinkFormat: false,
            cleanPastedHTML: false,
            delay: 0,
            diffLeft: 0,
            diffTop: -10,
            disableReturn: false,
            disableDoubleReturn: false,
            disableToolbar: false,
            disableEditing: false,
            elementsContainer: false,
            firstHeader: 'h3',
            forcePlainText: true,
            placeholder: 'Type your text',
            secondHeader: 'h4',
            targetBlank: false,
            extensions: {}
        },

        // http://stackoverflow.com/questions/17907445/how-to-detect-ie11#comment30165888_17907562
        // by rg89
        isIE: ((navigator.appName === 'Microsoft Internet Explorer') || ((navigator.appName === 'Netscape') && (new RegExp('Trident/.*rv:([0-9]{1,}[.0-9]{0,})').exec(navigator.userAgent) !== null))),

        init: function (elements, options) {
            this.setElementSelection(elements);
            if (this.elements.length === 0) {
                return;
            }
            this.parentElements = ['p', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'blockquote', 'pre'];
            this.id = document.querySelectorAll('.medium-editor-toolbar').length + 1;
            this.options = extend(options, this.defaults);
            return this.setup();
        },

        setup: function () {
            this.isActive = true;
            this.initElements()
                .bindSelect()
                .bindPaste()
                .setPlaceholders()
                .bindWindowActions();
        },

        initElements: function () {
            this.updateElementList();
            var i,
                addToolbar = false;
            for (i = 0; i < this.elements.length; i += 1) {
                if (!this.options.disableEditing && !this.elements[i].getAttribute('data-disable-editing')) {
                    this.elements[i].setAttribute('contentEditable', true);
                }
                if (!this.elements[i].getAttribute('data-placeholder')) {
                    this.elements[i].setAttribute('data-placeholder', this.options.placeholder);
                }
                this.elements[i].setAttribute('data-medium-element', true);
                this.bindParagraphCreation(i).bindReturn(i).bindTab(i);
                if (!this.options.disableToolbar && !this.elements[i].getAttribute('data-disable-toolbar')) {
                    addToolbar = true;
                }
            }
            // Init toolbar
            if (addToolbar) {
                if (!this.options.elementsContainer) {
                    this.options.elementsContainer = document.body;
                }
                this.initToolbar()
                    .bindButtons()
                    .bindAnchorForm()
                    .bindAnchorPreview();
            }
            return this;
        },

        setElementSelection: function (selector) {
            this.elementSelection = selector;
            this.updateElementList();
        },

        updateElementList: function () {
            this.elements = typeof this.elementSelection === 'string' ? document.querySelectorAll(this.elementSelection) : this.elementSelection;
            if (this.elements.nodeType === 1) {
                this.elements = [this.elements];
            }
        },

        serialize: function () {
            var i,
                elementid,
                content = {};
            for (i = 0; i < this.elements.length; i += 1) {
                elementid = (this.elements[i].id !== '') ? this.elements[i].id : 'element-' + i;
                content[elementid] = {
                    value: this.elements[i].innerHTML.trim()
                };
            }
            return content;
        },

        /**
         * Helper function to call a method with a number of parameters on all registered extensions.
         * The function assures that the function exists before calling.
         *
         * @param {string} funcName name of the function to call
         * @param [args] arguments passed into funcName
         */
        callExtensions: function (funcName) {
            if (arguments.length < 1) {
                return;
            }

            var args = Array.prototype.slice.call(arguments, 1),
                ext,
                name;

            for (name in this.options.extensions) {
                if (this.options.extensions.hasOwnProperty(name)) {
                    ext = this.options.extensions[name];
                    if (ext[funcName] !== undefined) {
                        ext[funcName].apply(ext, args);
                    }
                }
            }
        },

        bindParagraphCreation: function (index) {
            var self = this;
            this.elements[index].addEventListener('keypress', function (e) {
                var node = getSelectionStart(),
                    tagName;
                if (e.which === 32) {
                    tagName = node.tagName.toLowerCase();
                    if (tagName === 'a') {
                        document.execCommand('unlink', false, null);
                    }
                }
            });

            this.elements[index].addEventListener('keyup', function (e) {
                var node = getSelectionStart(),
                    tagName;
                if (node && node.getAttribute('data-medium-element') && node.children.length === 0 && !(self.options.disableReturn || node.getAttribute('data-disable-return'))) {
                    document.execCommand('formatBlock', false, 'p');
                }
                if (e.which === 13) {
                    node = getSelectionStart();
                    tagName = node.tagName.toLowerCase();
                    if (!(self.options.disableReturn || this.getAttribute('data-disable-return')) &&
                        tagName !== 'li' && !self.isListItemChild(node)) {
                        if (!e.shiftKey) {
                            document.execCommand('formatBlock', false, 'p');
                        }
                        if (tagName === 'a') {
                            document.execCommand('unlink', false, null);
                        }
                    }
                }
            });
            return this;
        },

        isListItemChild: function (node) {
            var parentNode = node.parentNode,
                tagName = parentNode.tagName.toLowerCase();
            while (this.parentElements.indexOf(tagName) === -1 && tagName !== 'div') {
                if (tagName === 'li') {
                    return true;
                }
                parentNode = parentNode.parentNode;
                if (parentNode && parentNode.tagName) {
                    tagName = parentNode.tagName.toLowerCase();
                } else {
                    return false;
                }
            }
            return false;
        },

        bindReturn: function (index) {
            var self = this;
            this.elements[index].addEventListener('keypress', function (e) {
                if (e.which === 13) {
                    if (self.options.disableReturn || this.getAttribute('data-disable-return')) {
                        e.preventDefault();
                    } else if (self.options.disableDoubleReturn || this.getAttribute('data-disable-double-return')) {
                        var node = getSelectionStart();
                        if (node && node.innerText === '\n') {
                            e.preventDefault();
                        }
                    }
                }
            });
            return this;
        },

        bindTab: function (index) {
            this.elements[index].addEventListener('keydown', function (e) {
                if (e.which === 9) {
                    // Override tab only for pre nodes
                    var tag = getSelectionStart().tagName.toLowerCase();
                    if (tag === 'pre') {
                        e.preventDefault();
                        document.execCommand('insertHtml', null, '    ');
                    }
                }
            });
            return this;
        },

        buttonTemplate: function (btnType) {
            var buttonLabels = this.getButtonLabels(this.options.buttonLabels),
                buttonTemplates = {
                    'bold': '<button class="medium-editor-action medium-editor-action-bold" data-action="bold" data-element="b">' + buttonLabels.bold + '</button>',
                    'italic': '<button class="medium-editor-action medium-editor-action-italic" data-action="italic" data-element="i">' + buttonLabels.italic + '</button>',
                    'underline': '<button class="medium-editor-action medium-editor-action-underline" data-action="underline" data-element="u">' + buttonLabels.underline + '</button>',
                    'strikethrough': '<button class="medium-editor-action medium-editor-action-strikethrough" data-action="strikethrough" data-element="strike"><strike>A</strike></button>',
                    'superscript': '<button class="medium-editor-action medium-editor-action-superscript" data-action="superscript" data-element="sup">' + buttonLabels.superscript + '</button>',
                    'subscript': '<button class="medium-editor-action medium-editor-action-subscript" data-action="subscript" data-element="sub">' + buttonLabels.subscript + '</button>',
                    'anchor': '<button class="medium-editor-action medium-editor-action-anchor" data-action="anchor" data-element="a">' + buttonLabels.anchor + '</button>',
                    'image': '<button class="medium-editor-action medium-editor-action-image" data-action="image" data-element="img">' + buttonLabels.image + '</button>',
                    'header1': '<button class="medium-editor-action medium-editor-action-header1" data-action="append-' + this.options.firstHeader + '" data-element="' + this.options.firstHeader + '">' + buttonLabels.header1 + '</button>',
                    'header2': '<button class="medium-editor-action medium-editor-action-header2" data-action="append-' + this.options.secondHeader + '" data-element="' + this.options.secondHeader + '">' + buttonLabels.header2 + '</button>',
                    'quote': '<button class="medium-editor-action medium-editor-action-quote" data-action="append-blockquote" data-element="blockquote">' + buttonLabels.quote + '</button>',
                    'orderedlist': '<button class="medium-editor-action medium-editor-action-orderedlist" data-action="insertorderedlist" data-element="ol">' + buttonLabels.orderedlist + '</button>',
                    'unorderedlist': '<button class="medium-editor-action medium-editor-action-unorderedlist" data-action="insertunorderedlist" data-element="ul">' + buttonLabels.unorderedlist + '</button>',
                    'pre': '<button class="medium-editor-action medium-editor-action-pre" data-action="append-pre" data-element="pre">' + buttonLabels.pre + '</button>',
                    'indent': '<button class="medium-editor-action medium-editor-action-indent" data-action="indent" data-element="ul">' + buttonLabels.indent + '</button>',
                    'outdent': '<button class="medium-editor-action medium-editor-action-outdent" data-action="outdent" data-element="ul">' + buttonLabels.outdent + '</button>'
                };
            return buttonTemplates[btnType] || false;
        },

        // TODO: break method
        getButtonLabels: function (buttonLabelType) {
            var customButtonLabels,
                attrname,
                buttonLabels = {
                    'bold': '<b>B</b>',
                    'italic': '<b><i>I</i></b>',
                    'underline': '<b><u>U</u></b>',
                    'superscript': '<b>x<sup>1</sup></b>',
                    'subscript': '<b>x<sub>1</sub></b>',
                    'anchor': '<b>#</b>',
                    'image': '<b>image</b>',
                    'header1': '<b>H1</b>',
                    'header2': '<b>H2</b>',
                    'quote': '<b>&ldquo;</b>',
                    'orderedlist': '<b>1.</b>',
                    'unorderedlist': '<b>&bull;</b>',
                    'pre': '<b>0101</b>',
                    'indent': '<b>&rarr;</b>',
                    'outdent': '<b>&larr;</b>'
                };
            if (buttonLabelType === 'fontawesome') {
                customButtonLabels = {
                    'bold': '<i class="fa fa-bold"></i>',
                    'italic': '<i class="fa fa-italic"></i>',
                    'underline': '<i class="fa fa-underline"></i>',
                    'superscript': '<i class="fa fa-superscript"></i>',
                    'subscript': '<i class="fa fa-subscript"></i>',
                    'anchor': '<i class="fa fa-link"></i>',
                    'image': '<i class="fa fa-picture-o"></i>',
                    'quote': '<i class="fa fa-quote-right"></i>',
                    'orderedlist': '<i class="fa fa-list-ol"></i>',
                    'unorderedlist': '<i class="fa fa-list-ul"></i>',
                    'pre': '<i class="fa fa-code fa-lg"></i>',
                    'indent': '<i class="fa fa-indent"></i>',
                    'outdent': '<i class="fa fa-outdent"></i>'
                };
            } else if (typeof buttonLabelType === 'object') {
                customButtonLabels = buttonLabelType;
            }
            if (typeof customButtonLabels === 'object') {
                for (attrname in customButtonLabels) {
                    if (customButtonLabels.hasOwnProperty(attrname)) {
                        buttonLabels[attrname] = customButtonLabels[attrname];
                    }
                }
            }
            return buttonLabels;
        },

        initToolbar: function () {
            if (this.toolbar) {
                return this;
            }
            this.toolbar = this.createToolbar();
            this.keepToolbarAlive = false;
            this.anchorForm = this.toolbar.querySelector('.medium-editor-toolbar-form-anchor');
            this.anchorInput = this.anchorForm.querySelector('input');
            this.toolbarActions = this.toolbar.querySelector('.medium-editor-toolbar-actions');
            this.anchorPreview = this.createAnchorPreview();

            return this;
        },

        createToolbar: function () {
            var toolbar = document.createElement('div');
            toolbar.id = 'medium-editor-toolbar-' + this.id;
            toolbar.className = 'medium-editor-toolbar';
            toolbar.appendChild(this.toolbarButtons());
            toolbar.appendChild(this.toolbarFormAnchor());
            this.options.elementsContainer.appendChild(toolbar);
            return toolbar;
        },

        //TODO: actionTemplate
        toolbarButtons: function () {
            var btns = this.options.buttons,
                ul = document.createElement('ul'),
                li,
                i,
                btn,
                ext;

            ul.id = 'medium-editor-toolbar-actions';
            ul.className = 'medium-editor-toolbar-actions clearfix';

            for (i = 0; i < btns.length; i += 1) {
                if (this.options.extensions.hasOwnProperty(btns[i])) {
                    ext = this.options.extensions[btns[i]];
                    btn = ext.getButton !== undefined ? ext.getButton() : null;
                } else {
                    btn = this.buttonTemplate(btns[i]);
                }

                if (btn) {
                    li = document.createElement('li');
                    if (isElement(btn)) {
                        li.appendChild(btn);
                    } else {
                        li.innerHTML = btn;
                    }
                    ul.appendChild(li);
                }
            }

            return ul;
        },

        toolbarFormAnchor: function () {
            var anchor = document.createElement('div'),
                input = document.createElement('input'),
                a = document.createElement('a');

            a.setAttribute('href', '#');
            a.innerHTML = '&times;';

            input.setAttribute('type', 'text');
            input.setAttribute('placeholder', this.options.anchorInputPlaceholder);

            anchor.className = 'medium-editor-toolbar-form-anchor';
            anchor.id = 'medium-editor-toolbar-form-anchor';
            anchor.appendChild(input);
            anchor.appendChild(a);

            return anchor;
        },

        bindSelect: function () {
            var self = this,
                timer = '',
                i;

            this.checkSelectionWrapper = function (e) {

                // Do not close the toolbar when bluring the editable area and clicking into the anchor form
                if (e && self.clickingIntoArchorForm(e)) {
                    return false;
                }

                clearTimeout(timer);
                timer = setTimeout(function () {
                    self.checkSelection();
                }, self.options.delay);
            };

            document.documentElement.addEventListener('mouseup', this.checkSelectionWrapper);

            for (i = 0; i < this.elements.length; i += 1) {
                this.elements[i].addEventListener('keyup', this.checkSelectionWrapper);
                this.elements[i].addEventListener('blur', this.checkSelectionWrapper);
            }
            return this;
        },

        checkSelection: function () {
            var newSelection,
                selectionElement;

            if (this.keepToolbarAlive !== true && !this.options.disableToolbar) {
                newSelection = window.getSelection();
                if (newSelection.toString().trim() === '' ||
                    (this.options.allowMultiParagraphSelection === false && this.hasMultiParagraphs())) {
                    this.hideToolbarActions();
                } else {
                    selectionElement = this.getSelectionElement();
                    if (!selectionElement || selectionElement.getAttribute('data-disable-toolbar')) {
                        this.hideToolbarActions();
                    } else {
                        this.checkSelectionElement(newSelection, selectionElement);
                    }
                }
            }
            return this;
        },

        clickingIntoArchorForm: function (e) {
            var self = this;
            if (e.type && e.type.toLowerCase() === 'blur' && e.relatedTarget && e.relatedTarget === self.anchorInput) {
                return true;
            }
            return false;
        },

        hasMultiParagraphs: function () {
            var selectionHtml = getSelectionHtml().replace(/<[\S]+><\/[\S]+>/gim, ''),
                hasMultiParagraphs = selectionHtml.match(/<(p|h[0-6]|blockquote)>([\s\S]*?)<\/(p|h[0-6]|blockquote)>/g);

            return (hasMultiParagraphs ? hasMultiParagraphs.length : 0);
        },

        checkSelectionElement: function (newSelection, selectionElement) {
            var i;
            this.selection = newSelection;
            this.selectionRange = this.selection.getRangeAt(0);
            for (i = 0; i < this.elements.length; i += 1) {
                if (this.elements[i] === selectionElement) {
                    this.setToolbarButtonStates()
                        .setToolbarPosition()
                        .showToolbarActions();
                    return;
                }
            }
            this.hideToolbarActions();
        },

        getSelectionElement: function () {
            var selection = window.getSelection(),
                range, current, parent,
                result,
                getMediumElement = function (e) {
                    var localParent = e;
                    try {
                        while (!localParent.getAttribute('data-medium-element')) {
                            localParent = localParent.parentNode;
                        }
                    } catch (errb) {
                        return false;
                    }
                    return localParent;
                };
            // First try on current node
            try {
                range = selection.getRangeAt(0);
                current = range.commonAncestorContainer;
                parent = current.parentNode;

                if (current.getAttribute('data-medium-element')) {
                    result = current;
                } else {
                    result = getMediumElement(parent);
                }
                // If not search in the parent nodes.
            } catch (err) {
                result = getMediumElement(parent);
            }
            return result;
        },

        setToolbarPosition: function () {
            var buttonHeight = 50,
                selection = window.getSelection(),
                range = selection.getRangeAt(0),
                boundary = range.getBoundingClientRect(),
                defaultLeft = (this.options.diffLeft) - (this.toolbar.offsetWidth / 2),
                middleBoundary = (boundary.left + boundary.right) / 2,
                halfOffsetWidth = this.toolbar.offsetWidth / 2;
            if (boundary.top < buttonHeight) {
                this.toolbar.classList.add('medium-toolbar-arrow-over');
                this.toolbar.classList.remove('medium-toolbar-arrow-under');
                this.toolbar.style.top = buttonHeight + boundary.bottom - this.options.diffTop + window.pageYOffset - this.toolbar.offsetHeight + 'px';
            } else {
                this.toolbar.classList.add('medium-toolbar-arrow-under');
                this.toolbar.classList.remove('medium-toolbar-arrow-over');
                this.toolbar.style.top = boundary.top + this.options.diffTop + window.pageYOffset - this.toolbar.offsetHeight + 'px';
            }
            if (middleBoundary < halfOffsetWidth) {
                this.toolbar.style.left = defaultLeft + halfOffsetWidth + 'px';
            } else if ((window.innerWidth - middleBoundary) < halfOffsetWidth) {
                this.toolbar.style.left = window.innerWidth + defaultLeft - halfOffsetWidth + 'px';
            } else {
                this.toolbar.style.left = defaultLeft + middleBoundary + 'px';
            }

            this.hideAnchorPreview();

            return this;
        },

        setToolbarButtonStates: function () {
            var buttons = this.toolbarActions.querySelectorAll('button'),
                i;
            for (i = 0; i < buttons.length; i += 1) {
                buttons[i].classList.remove('medium-editor-button-active');
            }
            this.checkActiveButtons();
            return this;
        },

        checkActiveButtons: function () {
            var elements = Array.prototype.slice.call(this.elements),
                parentNode = this.getSelectedParentElement();
            while (parentNode.tagName !== undefined && this.parentElements.indexOf(parentNode.tagName.toLowerCase) === -1) {
                this.activateButton(parentNode.tagName.toLowerCase());
                this.callExtensions('checkState', parentNode);

                // we can abort the search upwards if we leave the contentEditable element
                if (elements.indexOf(parentNode) !== -1) {
                    break;
                }
                parentNode = parentNode.parentNode;
            }
        },

        activateButton: function (tag) {
            var el = this.toolbar.querySelector('[data-element="' + tag + '"]');
            if (el !== null && el.className.indexOf('medium-editor-button-active') === -1) {
                el.className += ' medium-editor-button-active';
            }
        },

        bindButtons: function () {
            var buttons = this.toolbar.querySelectorAll('button'),
                i,
                self = this,
                triggerAction = function (e) {
                    e.preventDefault();
                    e.stopPropagation();
                    if (self.selection === undefined) {
                        self.checkSelection();
                    }
                    if (this.className.indexOf('medium-editor-button-active') > -1) {
                        this.classList.remove('medium-editor-button-active');
                    } else {
                        this.className += ' medium-editor-button-active';
                    }
                    if (this.hasAttribute('data-action')) {
                        self.execAction(this.getAttribute('data-action'), e);
                    }
                };
            for (i = 0; i < buttons.length; i += 1) {
                buttons[i].addEventListener('click', triggerAction);
            }
            this.setFirstAndLastItems(buttons);
            return this;
        },

        setFirstAndLastItems: function (buttons) {
            if (buttons.length > 0) {
                buttons[0].className += ' medium-editor-button-first';
                buttons[buttons.length - 1].className += ' medium-editor-button-last';
            }
            return this;
        },

        execAction: function (action, e) {
            if (action.indexOf('append-') > -1) {
                this.execFormatBlock(action.replace('append-', ''));
                this.setToolbarPosition();
                this.setToolbarButtonStates();
            } else if (action === 'anchor') {
                this.triggerAnchorAction(e);
            } else if (action === 'image') {
                document.execCommand('insertImage', false, window.getSelection());
            } else {
                document.execCommand(action, false, null);
                this.setToolbarPosition();
            }
        },

        // http://stackoverflow.com/questions/15867542/range-object-get-selection-parent-node-chrome-vs-firefox
        rangeSelectsSingleNode: function (range) {
            var startNode = range.startContainer;
            return startNode === range.endContainer &&
                startNode.hasChildNodes() &&
                range.endOffset === range.startOffset + 1;
        },

        getSelectedParentElement: function () {
            var selectedParentElement = null,
                range = this.selectionRange;
            if (this.rangeSelectsSingleNode(range)) {
                selectedParentElement = range.startContainer.childNodes[range.startOffset];
            } else if (range.startContainer.nodeType === 3) {
                selectedParentElement = range.startContainer.parentNode;
            } else {
                selectedParentElement = range.startContainer;
            }
            return selectedParentElement;
        },

        triggerAnchorAction: function () {
            var selectedParentElement = this.getSelectedParentElement();
            if (selectedParentElement.tagName &&
                    selectedParentElement.tagName.toLowerCase() === 'a') {
                document.execCommand('unlink', false, null);
            } else {
                if (this.anchorForm.style.display === 'block') {
                    this.showToolbarActions();
                } else {
                    this.showAnchorForm();
                }
            }
            return this;
        },

        execFormatBlock: function (el) {
            var selectionData = this.getSelectionData(this.selection.anchorNode);
            // FF handles blockquote differently on formatBlock
            // allowing nesting, we need to use outdent
            // https://developer.mozilla.org/en-US/docs/Rich-Text_Editing_in_Mozilla
            if (el === 'blockquote' && selectionData.el &&
                selectionData.el.parentNode.tagName.toLowerCase() === 'blockquote') {
                return document.execCommand('outdent', false, null);
            }
            if (selectionData.tagName === el) {
                el = 'p';
            }
            // When IE we need to add <> to heading elements and
            //  blockquote needs to be called as indent
            // http://stackoverflow.com/questions/10741831/execcommand-formatblock-headings-in-ie
            // http://stackoverflow.com/questions/1816223/rich-text-editor-with-blockquote-function/1821777#1821777
            if (this.isIE) {
                if (el === 'blockquote') {
                    return document.execCommand('indent', false, el);
                }
                el = '<' + el + '>';
            }
            return document.execCommand('formatBlock', false, el);
        },

        getSelectionData: function (el) {
            var tagName;

            if (el && el.tagName) {
                tagName = el.tagName.toLowerCase();
            }

            while (el && this.parentElements.indexOf(tagName) === -1) {
                el = el.parentNode;
                if (el && el.tagName) {
                    tagName = el.tagName.toLowerCase();
                }
            }

            return {
                el: el,
                tagName: tagName
            };
        },

        getFirstChild: function (el) {
            var firstChild = el.firstChild;
            while (firstChild !== null && firstChild.nodeType !== 1) {
                firstChild = firstChild.nextSibling;
            }
            return firstChild;
        },

        hideToolbarActions: function () {
            this.keepToolbarAlive = false;
            if (this.toolbar !== undefined) {
                this.toolbar.classList.remove('medium-editor-toolbar-active');
            }
        },

        showToolbarActions: function () {
            var self = this,
                timer;
            this.anchorForm.style.display = 'none';
            this.toolbarActions.style.display = 'block';
            this.keepToolbarAlive = false;
            clearTimeout(timer);
            timer = setTimeout(function () {
                if (self.toolbar && !self.toolbar.classList.contains('medium-editor-toolbar-active')) {
                    self.toolbar.classList.add('medium-editor-toolbar-active');
                }
            }, 100);
        },

        showAnchorForm: function (link_value) {
            this.toolbarActions.style.display = 'none';
            this.savedSelection = saveSelection();
            this.anchorForm.style.display = 'block';
            this.keepToolbarAlive = true;
            this.anchorInput.focus();
            this.anchorInput.value = link_value || '';
        },

        bindAnchorForm: function () {
            var linkCancel = this.anchorForm.querySelector('a'),
                self = this;
            this.anchorForm.addEventListener('click', function (e) {
                e.stopPropagation();
            });
            this.anchorInput.addEventListener('keyup', function (e) {
                if (e.keyCode === 13) {
                    e.preventDefault();
                    self.createLink(this);
                }
            });
            this.anchorInput.addEventListener('click', function (e) {
                // make sure not to hide form when cliking into the input
                e.stopPropagation();
                self.keepToolbarAlive = true;
            });
            this.anchorInput.addEventListener('blur', function () {
                self.keepToolbarAlive = false;
                self.checkSelection();
            });
            linkCancel.addEventListener('click', function (e) {
                e.preventDefault();
                self.showToolbarActions();
                restoreSelection(self.savedSelection);
            });
            return this;
        },


        hideAnchorPreview: function () {
            this.anchorPreview.classList.remove('medium-editor-anchor-preview-active');
        },

        // TODO: break method
        showAnchorPreview: function (anchorEl) {
            if (this.anchorPreview.classList.contains('medium-editor-anchor-preview-active')) {
                return true;
            }

            var self = this,
                buttonHeight = 40,
                boundary = anchorEl.getBoundingClientRect(),
                middleBoundary = (boundary.left + boundary.right) / 2,
                halfOffsetWidth,
                defaultLeft,
                timer;

            self.anchorPreview.querySelector('i').textContent = anchorEl.href;
            halfOffsetWidth = self.anchorPreview.offsetWidth / 2;
            defaultLeft = self.options.diffLeft - halfOffsetWidth;

            clearTimeout(timer);
            timer = setTimeout(function () {
                if (self.anchorPreview && !self.anchorPreview.classList.contains('medium-editor-anchor-preview-active')) {
                    self.anchorPreview.classList.add('medium-editor-anchor-preview-active');
                }
            }, 100);

            self.observeAnchorPreview(anchorEl);

            self.anchorPreview.classList.add('medium-toolbar-arrow-over');
            self.anchorPreview.classList.remove('medium-toolbar-arrow-under');
            self.anchorPreview.style.top = Math.round(buttonHeight + boundary.bottom - self.options.diffTop + window.pageYOffset - self.anchorPreview.offsetHeight) + 'px';
            if (middleBoundary < halfOffsetWidth) {
                self.anchorPreview.style.left = defaultLeft + halfOffsetWidth + 'px';
            } else if ((window.innerWidth - middleBoundary) < halfOffsetWidth) {
                self.anchorPreview.style.left = window.innerWidth + defaultLeft - halfOffsetWidth + 'px';
            } else {
                self.anchorPreview.style.left = defaultLeft + middleBoundary + 'px';
            }

            return this;
        },

        // TODO: break method
        observeAnchorPreview: function (anchorEl) {
            var self = this,
                lastOver = (new Date()).getTime(),
                over = true,
                stamp = function () {
                    lastOver = (new Date()).getTime();
                    over = true;
                },
                unstamp = function (e) {
                    if (!e.relatedTarget || !/anchor-preview/.test(e.relatedTarget.className)) {
                        over = false;
                    }
                },
                interval_timer = setInterval(function () {
                    if (over) {
                        return true;
                    }
                    var durr = (new Date()).getTime() - lastOver;
                    if (durr > self.options.anchorPreviewHideDelay) {
                        // hide the preview 1/2 second after mouse leaves the link
                        self.hideAnchorPreview();

                        // cleanup
                        clearInterval(interval_timer);
                        self.anchorPreview.removeEventListener('mouseover', stamp);
                        self.anchorPreview.removeEventListener('mouseout', unstamp);
                        anchorEl.removeEventListener('mouseover', stamp);
                        anchorEl.removeEventListener('mouseout', unstamp);

                    }
                }, 200);

            self.anchorPreview.addEventListener('mouseover', stamp);
            self.anchorPreview.addEventListener('mouseout', unstamp);
            anchorEl.addEventListener('mouseover', stamp);
            anchorEl.addEventListener('mouseout', unstamp);
        },

        createAnchorPreview: function () {
            var self = this,
                anchorPreview = document.createElement('div');

            anchorPreview.id = 'medium-editor-anchor-preview-' + this.id;
            anchorPreview.className = 'medium-editor-anchor-preview';
            anchorPreview.innerHTML = this.anchorPreviewTemplate();
            this.options.elementsContainer.appendChild(anchorPreview);

            anchorPreview.addEventListener('click', function () {
                self.anchorPreviewClickHandler();
            });

            return anchorPreview;
        },

        anchorPreviewTemplate: function () {
            return '<div class="medium-editor-toolbar-anchor-preview" id="medium-editor-toolbar-anchor-preview">' +
                '    <i class="medium-editor-toolbar-anchor-preview-inner"></i>' +
                '</div>';
        },

        anchorPreviewClickHandler: function (e) {
            if (this.activeAnchor) {

                var self = this,
                    range = document.createRange(),
                    sel = window.getSelection();

                range.selectNodeContents(self.activeAnchor);
                sel.removeAllRanges();
                sel.addRange(range);
                setTimeout(function () {
                    if (self.activeAnchor) {
                        self.showAnchorForm(self.activeAnchor.href);
                    }
                    self.keepToolbarAlive = false;
                }, 100 + self.options.delay);

            }

            this.hideAnchorPreview();
        },

        editorAnchorObserver: function (e) {
            var self = this,
                overAnchor = true,
                leaveAnchor = function () {
                    // mark the anchor as no longer hovered, and stop listening
                    overAnchor = false;
                    self.activeAnchor.removeEventListener('mouseout', leaveAnchor);
                };

            if (e.target && e.target.tagName.toLowerCase() === 'a') {

                // Detect empty href attributes
                // The browser will make href="" or href="#top"
                // into absolute urls when accessed as e.targed.href, so check the html
                if (!/href=["']\S+["']/.test(e.target.outerHTML) || /href=["']#\S+["']/.test(e.target.outerHTML)) {
                    return true;
                }

                // only show when hovering on anchors
                if (this.toolbar.classList.contains('medium-editor-toolbar-active')) {
                    // only show when toolbar is not present
                    return true;
                }
                this.activeAnchor = e.target;
                this.activeAnchor.addEventListener('mouseout', leaveAnchor);
                // show the anchor preview according to the configured delay
                // if the mouse has not left the anchor tag in that time
                setTimeout(function () {
                    if (overAnchor) {
                        self.showAnchorPreview(e.target);
                    }
                }, self.options.delay);


            }
        },

        bindAnchorPreview: function (index) {
            var i, self = this;
            this.editorAnchorObserverWrapper = function (e) {
                self.editorAnchorObserver(e);
            };
            for (i = 0; i < this.elements.length; i += 1) {
                this.elements[i].addEventListener('mouseover', this.editorAnchorObserverWrapper);
            }
            return this;
        },

        checkLinkFormat: function (value) {
            var re = /^https?:\/\//;
            if (value.match(re)) {
                return value;
            }
            return "http://" + value;
        },

        setTargetBlank: function () {
            var el = getSelectionStart(),
                i;
            if (el.tagName.toLowerCase() === 'a') {
                el.target = '_blank';
            } else {
                el = el.getElementsByTagName('a');
                for (i = 0; i < el.length; i += 1) {
                    el[i].target = '_blank';
                }
            }
        },

        createLink: function (input) {
            restoreSelection(this.savedSelection);
            if (this.options.checkLinkFormat) {
                input.value = this.checkLinkFormat(input.value);
            }
            document.execCommand('createLink', false, input.value);
            if (this.options.targetBlank) {
                this.setTargetBlank();
            }
            this.checkSelection();
            this.showToolbarActions();
            input.value = '';
        },

        bindWindowActions: function () {
            var timerResize,
                self = this;
            this.windowResizeHandler = function () {
                clearTimeout(timerResize);
                timerResize = setTimeout(function () {
                    if (self.toolbar && self.toolbar.classList.contains('medium-editor-toolbar-active')) {
                        self.setToolbarPosition();
                    }
                }, 100);
            };
            window.addEventListener('resize', this.windowResizeHandler);
            return this;
        },

        activate: function () {
            if (this.isActive) {
                return;
            }

            this.setup();
        },

        // TODO: break method
        deactivate: function () {
            var i;
            if (!this.isActive) {
                return;
            }
            this.isActive = false;

            if (this.toolbar !== undefined) {
                this.options.elementsContainer.removeChild(this.anchorPreview);
                this.options.elementsContainer.removeChild(this.toolbar);
                delete this.toolbar;
                delete this.anchorPreview;
            }

            document.documentElement.removeEventListener('mouseup', this.checkSelectionWrapper);
            window.removeEventListener('resize', this.windowResizeHandler);

            for (i = 0; i < this.elements.length; i += 1) {
                this.elements[i].removeEventListener('mouseover', this.editorAnchorObserverWrapper);
                this.elements[i].removeEventListener('keyup', this.checkSelectionWrapper);
                this.elements[i].removeEventListener('blur', this.checkSelectionWrapper);
                this.elements[i].removeEventListener('paste', this.pasteWrapper);
                this.elements[i].removeAttribute('contentEditable');
                this.elements[i].removeAttribute('data-medium-element');
            }

        },

        htmlEntities: function (str) {
            // converts special characters (like <) into their escaped/encoded values (like &lt;).
            // This allows you to show to display the string without the browser reading it as HTML.
            return String(str).replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;').replace(/"/g, '&quot;');
        },

        bindPaste: function () {
            var i, self = this;
            this.pasteWrapper = function (e) {
                var paragraphs,
                    html = '',
                    p;

                this.classList.remove('medium-editor-placeholder');
                if (!self.options.forcePlainText && !self.options.cleanPastedHTML) {
                    return this;
                }

                if (e.clipboardData && e.clipboardData.getData && !e.defaultPrevented) {
                    e.preventDefault();

                    if (self.options.cleanPastedHTML && e.clipboardData.getData('text/html')) {
                        return self.cleanPaste(e.clipboardData.getData('text/html'));
                    }
                    if (!(self.options.disableReturn || this.getAttribute('data-disable-return'))) {
                        paragraphs = e.clipboardData.getData('text/plain').split(/[\r\n]/g);
                        for (p = 0; p < paragraphs.length; p += 1) {
                            if (paragraphs[p] !== '') {
                                if (navigator.userAgent.match(/firefox/i) && p === 0) {
                                    html += self.htmlEntities(paragraphs[p]);
                                } else {
                                    html += '<p>' + self.htmlEntities(paragraphs[p]) + '</p>';
                                }
                            }
                        }
                        document.execCommand('insertHTML', false, html);
                    } else {
                        document.execCommand('insertHTML', false, e.clipboardData.getData('text/plain'));
                    }
                }
            };
            for (i = 0; i < this.elements.length; i += 1) {
                this.elements[i].addEventListener('paste', this.pasteWrapper);
            }
            return this;
        },

        setPlaceholders: function () {
            var i,
                activatePlaceholder = function (el) {
                    if (!(el.querySelector('img')) &&
                            el.textContent.replace(/^\s+|\s+$/g, '') === '') {
                        el.classList.add('medium-editor-placeholder');
                    }
                },
                placeholderWrapper = function (e) {
                    this.classList.remove('medium-editor-placeholder');
                    if (e.type !== 'keypress') {
                        activatePlaceholder(this);
                    }
                };
            for (i = 0; i < this.elements.length; i += 1) {
                activatePlaceholder(this.elements[i]);
                this.elements[i].addEventListener('blur', placeholderWrapper);
                this.elements[i].addEventListener('keypress', placeholderWrapper);
            }
            return this;
        },

        cleanPaste: function (text) {

            /*jslint regexp: true*/
            /*
                jslint does not allow character negation, because the negation
                will not match any unicode characters. In the regexes in this
                block, negation is used specifically to match the end of an html
                tag, and in fact unicode characters *should* be allowed.
            */
            var i, elList, workEl,
                el = this.getSelectionElement(),
                multiline = /<p|<br|<div/.test(text),
                replacements = [

                    // replace two bogus tags that begin pastes from google docs
                    [new RegExp(/<[^>]*docs-internal-guid[^>]*>/gi), ""],
                    [new RegExp(/<\/b>(<br[^>]*>)?$/gi), ""],

                     // un-html spaces and newlines inserted by OS X
                    [new RegExp(/<span class="Apple-converted-space">\s+<\/span>/g), ' '],
                    [new RegExp(/<br class="Apple-interchange-newline">/g), '<br>'],

                    // replace google docs italics+bold with a span to be replaced once the html is inserted
                    [new RegExp(/<span[^>]*(font-style:italic;font-weight:bold|font-weight:bold;font-style:italic)[^>]*>/gi), '<span class="replace-with italic bold">'],

                    // replace google docs italics with a span to be replaced once the html is inserted
                    [new RegExp(/<span[^>]*font-style:italic[^>]*>/gi), '<span class="replace-with italic">'],

                    //[replace google docs bolds with a span to be replaced once the html is inserted
                    [new RegExp(/<span[^>]*font-weight:bold[^>]*>/gi), '<span class="replace-with bold">'],

                     // replace manually entered b/i/a tags with real ones
                    [new RegExp(/&lt;(\/?)(i|b|a)&gt;/gi), '<$1$2>'],

                     // replace manually a tags with real ones, converting smart-quotes from google docs
                    [new RegExp(/&lt;a\s+href=(&quot;|&rdquo;|&ldquo;|“|”)([^&]+)(&quot;|&rdquo;|&ldquo;|“|”)&gt;/gi), '<a href="$2">']

                ];
            /*jslint regexp: false*/

            for (i = 0; i < replacements.length; i += 1) {
                text = text.replace(replacements[i][0], replacements[i][1]);
            }

            if (multiline) {

                // double br's aren't converted to p tags, but we want paragraphs.
                elList = text.split('<br><br>');

                this.pasteHTML('<p>' + elList.join('</p><p>') + '</p>');
                document.execCommand('insertText', false, "\n");

                // block element cleanup
                elList = el.querySelectorAll('p,div,br');
                for (i = 0; i < elList.length; i += 1) {

                    workEl = elList[i];

                    switch (workEl.tagName.toLowerCase()) {
                    case 'p':
                    case 'div':
                        this.filterCommonBlocks(workEl);
                        break;
                    case 'br':
                        this.filterLineBreak(workEl);
                        break;
                    }

                }


            } else {

                this.pasteHTML(text);

            }

        },

        pasteHTML: function (html) {
            var elList, workEl, i, fragmentBody, pasteBlock = document.createDocumentFragment();

            pasteBlock.appendChild(document.createElement('body'));

            fragmentBody = pasteBlock.querySelector('body');
            fragmentBody.innerHTML = html;

            this.cleanupSpans(fragmentBody);

            elList = fragmentBody.querySelectorAll('*');
            for (i = 0; i < elList.length; i += 1) {

                workEl = elList[i];

                // delete ugly attributes
                workEl.removeAttribute('class');
                workEl.removeAttribute('style');
                workEl.removeAttribute('dir');

                if (workEl.tagName.toLowerCase() === 'meta') {
                    workEl.parentNode.removeChild(workEl);
                }

            }
            document.execCommand('insertHTML', false, fragmentBody.innerHTML.replace(/&nbsp;/g, ' '));
        },
        isCommonBlock: function (el) {
            return (el && (el.tagName.toLowerCase() === 'p' || el.tagName.toLowerCase() === 'div'));
        },
        filterCommonBlocks: function (el) {
            if (/^\s*$/.test(el.innerText)) {
                el.parentNode.removeChild(el);
            }
        },
        filterLineBreak: function (el) {
            if (this.isCommonBlock(el.previousElementSibling)) {

                // remove stray br's following common block elements
                el.parentNode.removeChild(el);

            } else if (this.isCommonBlock(el.parentNode) && (el.parentNode.firstChild === el || el.parentNode.lastChild === el)) {

                // remove br's just inside open or close tags of a div/p
                el.parentNode.removeChild(el);

            } else if (el.parentNode.childElementCount === 1) {

                // and br's that are the only child of a div/p
                this.removeWithParent(el);

            }

        },

        // remove an element, including its parent, if it is the only element within its parent
        removeWithParent: function (el) {
            if (el && el.parentNode) {
                if (el.parentNode.parentNode && el.parentNode.childElementCount === 1) {
                    el.parentNode.parentNode.removeChild(el.parentNode);
                } else {
                    el.parentNode.removeChild(el.parentNode);
                }
            }
        },

        cleanupSpans: function (container_el) {

            var i,
                el,
                new_el,
                spans = container_el.querySelectorAll('.replace-with');

            for (i = 0; i < spans.length; i += 1) {

                el = spans[i];
                new_el = document.createElement(el.classList.contains('bold') ? 'b' : 'i');

                if (el.classList.contains('bold') && el.classList.contains('italic')) {

                    // add an i tag as well if this has both italics and bold
                    new_el.innerHTML = '<i>' + el.innerHTML + '</i>';

                } else {

                    new_el.innerHTML = el.innerHTML;

                }
                el.parentNode.replaceChild(new_el, el);

            }

            spans = container_el.querySelectorAll('span');
            for (i = 0; i < spans.length; i += 1) {

                el = spans[i];

                // remove empty spans, replace others with their contents
                if (/^\s*$/.test()) {
                    el.parentNode.removeChild(el);
                } else {
                    el.parentNode.replaceChild(document.createTextNode(el.innerText), el);
                }

            }

        }

    };

}(window, document));
